The present disclosure is related to an objective lens for endoscopes and to an endoscope equipped with the objective lens for endoscopes.
Conventionally, endoscopes of the insertion type, in which an elongate insertion portion having an imaging device built in at the distal end portion thereof is inserted through the mouth or the nose of a patient to image the interiors of body cavities, are in common use in the medical field. Known objective lenses which are utilizable in such endoscopes are disclosed in Japanese Unexamined Patent Publication No. H9(1997)-269450, Japanese Patent No. 3574484, and Japanese Unexamined Patent Publication No. 2009-080413, for example. Japanese Unexamined Patent Publication No. H9(1997)-269450 and Japanese Patent No. 3574484 disclose lens systems having four lenses, and Japanese Unexamined Patent Publication No. 2009-080413 discloses lens systems in which the number of lenses is within a range from four to six.